diff options
| author | Yu Kuai <yukuai@fygo.io> | 2026-06-08 11:42:48 +0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-06-24 06:42:31 -0600 |
| commit | f928145cbcb52544203808f159461d0a25543df7 (patch) | |
| tree | 0201c905471e68e84e7f2242bd236ba194c3d336 /mm | |
| parent | 4cfd7c1cff8f4c863b99d420cdbe0563802a9e80 (diff) | |
| download | linux-f928145cbcb52544203808f159461d0a25543df7.tar.gz linux-f928145cbcb52544203808f159461d0a25543df7.zip | |
mm/page_io: don't nest queue_lock under rcu in bio_associate_blkg_from_page()
Take a css reference under RCU, drop RCU, and then associate the bio with
the blkg. This avoids nesting queue_lock under RCU and prepares to protect
blkcg with blkcg_mutex instead of queue_lock.
Use css_tryget() instead of css_tryget_online() so swap writeback for
pages charged to a dying memcg still passes the dying css to
bio_associate_blkg_from_css(). That preserves the existing closest-live
ancestor fallback instead of charging those bios to the root blkg.
Signed-off-by: Yu Kuai <yukuai@fygo.io>
Link: https://patch.msgid.link/c910d2c39d3ec97f67de68af636a52394342d55f.1780621988.git.yukuai@fygo.io
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/page_io.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/mm/page_io.c b/mm/page_io.c index a59b73f8bdd9..c96d3e4cf872 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -317,8 +317,13 @@ static void bio_associate_blkg_from_page(struct bio *bio, struct folio *folio) rcu_read_lock(); memcg = folio_memcg(folio); css = cgroup_e_css(memcg->css.cgroup, &io_cgrp_subsys); - bio_associate_blkg_from_css(bio, css); + if (!css || !css_tryget(css)) + css = NULL; rcu_read_unlock(); + + bio_associate_blkg_from_css(bio, css); + if (css) + css_put(css); } #else #define bio_associate_blkg_from_page(bio, folio) do { } while (0) |